Method for manufacturing a porous oil-impregnated revolving shaft assembly

ABSTRACT

A method for manufacturing a porous oil-impregnated revolving shaft assembly includes following steps: 1) offering an amount of metal powder, a particle diameter of the metal powder ranging from 1 μm to 150 μm; 2) offering a mold cavity and filling the metal powder in the mold cavity to form a green piece, a plurality of pores being defined between the metal powder of the green piece; 3) heating the green piece at a high temperature to sinter the metal powder to obtain a sintered product, a volume ratio of pores of the sintered product ranging from 12% and 20%; 4) dipping the sintered product into oil to make the oil enter the pores of the sintered product to thereby obtain a final desired product for forming the porous oil-impregnated revolving shaft assembly.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for manufacturing a porous oil-impregnated revolving shaft assembly, and more particularly to a method for manufacturing a porous oil-impregnated revolving shaft assembly with multiple communicated pores receiving lubricating oil therein.

2. Description of related art

Generally, a revolving shaft assembly is used as a hinge in electronic devices, such as notebook, mobile phone, media player and so on. The revolving shaft assembly includes a driving member and a driven member interfereferingly and pivotally engaging with the driving member. Each of the driving member and the driven member has an inner surface intimately engages with each other. A plurality of holes is defined between the driving member and driven member to storage oil to lubricate the inner surfaces of the driving member and the driven member. A part of the inner surfaces of the driving member and the driven member where the oil can not reach is not lubricated. As a result, a serious friction occurs between the part of the inner surfaces of the driving member and the driven member and noise is unavoidable to occur after a period of use of the shaft assembly. The function and the lifespan of the revolving shaft assembly are accordingly affected and shortened.

It is therefore desirable to provide a method for manufacturing an improved revolving shaft assembly with a driving member and a driven member which can rotate smoothly relative to each other.

SUMMARY OF THE INVENTION

A method for manufacturing a porous oil-impregnated revolving shaft assembly includes following steps: 1) offering an amount of metal powder, a particle diameter of the metal powder ranging from 1 μm to 150 μm; 2) offering a mold having a cavity and filling the metal powder in the cavity of the mold to make a green piece, a plurality of pores being defined between the metal powder of the green piece; 3) heating the green piece at a high temperature to sinter the metal powder to obtain a sintered product, a volume ratio of pores of the sintered product ranging from 12% and 20%; 4) dipping the sintered product into oil to make the oil enter the pores of the sintered product thereby to obtain the desired final product.

Other advantages and novel features will become more apparent from the following detailed description of preferred embodiments when taken in conjunction with the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present embodiments can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present embodiments. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

FIG. 1 is an assembled view of a porous oil-impregnated revolving shaft assembly in accordance with a first embodiment of the present invention;

FIG. 2 is an exploded view of FIG. 1;

FIG. 3 is an inverted view of FIG. 2; and

FIG. 4 is a scanning electron micrograph of a section of a green piece for forming the porous oil-impregnated revolving shaft assembly of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1-3, a porous oil-impregnated revolving shaft assembly comprises a driving member 10 and a driven member 20 pivotally engaging with the driving member 10. The driving and driven members 10, 20 are provided to a shaft (not shown) passing therethrough in series. The driving member 10 rotates with the shaft synchronously. The driven member 20 is fixed to a main bracket (not shown). Each of the driving member 10 and the driven member 20 has an inner surfaces (not labeled) oriented towards each other. The inner surfaces of the driving member 10 and the driven member 20 intimately engage with each other. The driving member 10 and the driven member 20 can be rotated relative to each other.

Referring to FIG. 4 also, a method for manufacturing the porous oil-impregnated revolving shaft assembly in accordance with a first embodiment of the present invention comprises the steps of: 1) offering a quantity of fine metal powder (not labeled), each fine metal powder having a particle diameter ranging from 10 μm to 150 μm, wherein a particle diameter ranging from 50 μm to 80 μm is preferable; 2) offering a quantity of super fine metal powder (not labeled), each super fine metal powder having a particle diameter ranging from 1 μm to 10 μm; 3) mixing the fine metal powder and the super fine metal powder to have mixed powder; 4) offering a mold (not shown) having a cavity and filling the mixed powder into the cavity of the mold and pressing the mixed powder to make a green piece, wherein pores 30 are defined between the pressed mixed powder and a volume ratio of the pores 30 of the green piece is situated between 30% and 50%, and a volume ratio 35% of the pores 30 in the green piece is preferable; 5) heating the green piece at a high temperature, whereby the mixed powder of the green piece is sintered and diffusion bonded together to obtained a sintered product, wherein particles of the mixed powder after the sintering have approximately the same diameter to enhance the performance of the porous oil-impregnated revolving shaft assembly; and wherein a volume ratio of pores of the sintered product is situated between 5% and 30%, and a volume ratio of pores of the sintered product situated between 12% and 20% is preferable; 6) dipping the sintered product into oil to fill the oil in the pores 30 of the sintered product thereby to obtain a final desired product for forming the porous oil-impregnated revolving shaft assembly.

In this embodiment, the metal powder is manufactured by mechanical method, such as cutting, crushing, chipping, etc. Super fine metal powder acting as an additive is added to the fine metal powder to improve the sintering strength of the fine metal powder. The super fine metal powder accounts for 1%˜10% of the fine metal powder by weight. When the driving member 10 and the driven member are assembled together, inner surfaces of the driving member 10 and the driven member 20 are intimately engaged with each other. An oil film is formed between the inner surfaces of the driving member 10 and the driven member 20 to lubricate the whole of inner surfaces of the driving member 10 and the driven member 20. Thus, the driving member 10 and the driven member 20 can rotate smoothly relative to each other and the noise generated by the conventional revolving shaft assembly after a period of use thereof can be avoided by the present invention.

A method for manufacturing the porous oil-impregnated revolving shaft assembly in accordance with a second embodiment of the present invention comprises the steps of: 1) offering an amount of super fine metal powder (not shown), a particle diameter of each super fine metal powder ranging from 1 μm to 20 μm, wherein a particle diameter ranging from 5 μm to 20 μm is preferable; 2) offering a bonding agent (not shown) to mix with the super fine metal powder together to thereby obtain a mixture and injecting the mixture into a mold cavity (not shown) to obtain a green piece; 3) heating the green piece at a selected temperature to obtain a sintered product, wherein the super fine metal powder is sintered; 4) dipping the sintered product into oil to fill pores in the sintered product with the oil thereby to obtain a desired final product for forming the revolving shaft assembly.

In the second embodiment, the temperature of sintering is lower than that of the first embodiment, and the volume ratio of the porous of the desired final product is the same as that of the first embodiment.

It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention. 

1. A method for manufacturing a porous oil-impregnated revolving shaft assembly comprising the steps of: 1) offering a plurality of metal powder, a particle diameter of the metal powder ranging from 1 μm to 150 μm; 2) offering a mold cavity and filling the metal powder in the mold cavity to form a green piece, wherein a plurality of pores is defined between the metal powder of the green piece; 3) heating the green piece at a high temperature to sinter the metal powder to obtain a sintered product, wherein a volume ratio of pores of the sintered product ranges from 12% and 20%; 4) dipping the sintered product in oil to make the oil enter the pores of the sintered product to thereby obtain a final desired product.
 2. The method for manufacturing a porous oil-impregnated revolving shaft assembly as in claim 1, wherein the metal powder comprises an amount of fine metal powder and an amount of super fine metal powder, a particle diameter of the fine metal powder ranging from 10 μm to 150 μm.
 3. The method for manufacturing a porous oil-impregnated revolving shaft assembly as in claim 2, wherein the particle diameter of the fine metal powder ranges from 50 μm to 80 μm.
 4. The method for manufacturing a porous oil-impregnated revolving shaft assembly as in claim 2, wherein a particle diameter of the super fine metal powder ranges from 1 μm to 10 μm.
 5. The method for manufacturing a porous oil-impregnated revolving shaft assembly as in claim 2, wherein the super fine metal powder accounts for 1%˜10% of a weight of the fine metal powder.
 6. The method for manufacturing a porous oil-impregnated revolving shaft assembly as in claim 3, wherein the metal powder received in the mold cavity is pressed to make the green piece, a volume ratio of pores of the green piece situated between 30% and 50%.
 7. The method for manufacturing a porous oil-impregnated revolving shaft assembly as in claim 6, wherein the volume ratio of the pores of the green piece is situated at 35%.
 8. The method for manufacturing a porous oil-impregnated revolving shaft assembly as in claim 1, wherein a particle diameter of the metal powder ranges from 1 μm to 20 μm.
 9. The method for manufacturing a porous oil-impregnated revolving shaft assembly as in claim 8, wherein the particle diameter of the metal powder ranges from 5 μm to 20 μm.
 10. The method for manufacturing a porous oil-impregnated revolving shaft assembly as in claim 9, wherein a bonding agent mixes with the metal powder to make a mixture and the mixture is injected into the mold cavity to obtain the green piece. 